In the related art, an indexable grooving tool performing grooving, cutting-off, or the like (which will hereinafter be simply abbreviated to grooving sometimes) by cutting a cutting target material, which is formed of a metal material or the like and has a columnar shape or a cylindrical shape, with a cutting edge of a grooving cutting insert on an outer circumferential surface, an inner circumferential surface, end surfaces orientated in an axial line direction, and the like of the cutting target material while the cutting target material is rotated around an axial line is known.
For example, in an indexable grooving tool of PTL 1 referenced below, a slit-shaped insert mounting seat is formed in an insert holding plate portion of a distal end portion of a tool main body, and a grooving cutting insert having a cutting edge is mounted in the insert mounting seat in an attachable/detachable manner.
Specifically, a slit-shaped opening-closing operation slit communicating with the insert mounting seat is formed in the insert holding plate portion, and the grooving cutting insert can be easily attached and detached with respect to the insert mounting seat by performing an operation of inserting an eccentric body of a key into a keyhole of the opening-closing operation slit. Generally, the key is manufactured of a material harder than that of the tool main body.
A cross section of the eccentric body of the key has a substantially rectangular shape, and each of four corner portions thereof has a projected round shape. Then, when the eccentric body is inserted into the keyhole and a pair of long side regions in the outer circumference of the eccentric body is disposed to face an upper wall and a lower wall of the keyhole, a gap is formed between each of the upper wall and the lower wall, and each of the pair of long side regions.
If the eccentric body is rotated around its center axis by 90° and a pair of short side regions in the outer circumference of the eccentric body is disposed to face the upper wall and the lower wall of the keyhole by operating the key from this state, the short side regions pressurize the upper wall and the lower wall in an orientation of being separated from each other. As the upper wall and the lower wall of the keyhole are pressurized, a clamping finger (upper jaw portion) of the insert holding plate portion is elastically deformed. Consequently, a distance between a top wall and a bottom wall of the insert mounting seat increases, so that the grooving cutting insert can be inserted with respect to the insert mounting seat.
In addition, in a state where the grooving cutting insert is inserted in the insert mounting seat, if the key is operated again and the pair of long side regions of the eccentric body is disposed to face the upper wall and the lower wall of the keyhole, the clamping finger is deformed to be restored and the grooving cutting insert is clamped with respect to the insert mounting seat.
According to an insert clamping mechanism having such a configuration, the grooving cutting insert can be clamped without damaging the top wall or the bottom wall of the insert mounting seat.